Irrigation systems are used to provide controlled watering to vegetation zones and specific plants. There are various types of irrigation emission devices that can be used in irrigations systems. One type is an on-line drip emitter. An on-line drip emitter attaches onto a supply line and coverts the higher pressure flow in the supply line to a drip-like emission. Exemplary flow rates for drip emission can be in the range of 0.5 to 24.0 gallons per hour, and preferably about 0.5 to 2.0 gallons per hour.
In a typical irrigation system, there is a control valve upstream from the emission devices to control the flow to the emission devices. That is, during an irrigation event, the control valve is opened to allow flow to the emission devices, and conversely, between irrigation events, the control valve prohibits flow to the emission devices. An irrigation system may include many drip emitters mounted at selected positions along the length of a supply line to deliver irrigation water to a large number of specific points, including directly to a plurality of individual plants.
When a drip irrigation event is over, water can remain in the supply line from the control valve to the drip emitters. This remaining water can slowly escape through the drip emitters if there is nothing to prevent such flow. This is especially the case when the drip emitters are at a lower elevation than the control valve. This can cause unnecessary water use and overwatering.
There are on-line drip emitters available that include a check valve to prevent water from escaping from the supply line between irrigation events. However, most of these designs separate the pressure reduction feature from the pressure compensation feature or use a single diaphragm to cover all three functions of (1) a check valve, (2) pressure compensation and (3) sealing of the tortuous path. It would be beneficial to have a design that would permit the pressure compensation feature to be associated with the pressure reduction feature. It would be further beneficial to be able to adjust the hold-back capability of the check valve while also being able to minimize any changes to the pressure compensation feature of the emitter.